Levels of small extracellular vesicles in patients treated with hyperbaric oxygenation

Hyperbaric oxygen (HBO₂) therapy involves the inhalation of pure oxygen in a pressure chamber under increased ambient pressure. Recent research indicates that circulating small extracellular vesicles (sEVs) play important roles in human physiology and pathology. Therefore, the objective of this pilot study was to monitor the impact of HBO₂ therapy on the levels of circulating sEVs in the serum of patients with necrotizing soft-tissue infections (NSTI), aseptic bone necrosis (ABN) or idiopathic sudden sensory neural hearing loss (ISSNHL).

Serum-derived sEVs were isolated and quantified in 80 patients before and after HBO₂ therapy applied for NSTI, ISSNHL and ABN patients as well as in normal controls who received neither HBO₂ therapy nor steroids.

We observed a significant increase of circulating sEVs in patients with ISSNHL after HBO₂ therapy (p < 0.05), as well as significantly elevated levels of sEVs after HBO₂ therapy compared to patients with NSTI (p < 0.05) and ABN (p < 0.01).

The increase in the levels of sEVs in ISSNHL may be evidence for both the intended reduction of inflammation as a result of steroid therapy and the inhibitory effect of oxidative stress induced by HBO₂ therapy. Thus, sEVs released during HBO₂ therapy might play an important biological role in mediating the response to therapy and might be a promising approach to gain further insights into the therapeutic efficacy of HBO₂ therapy.